Crude oil and its fractions are used as feedstock for producing valuable chemicals. In the future, various high-value added biochemicals can also be commercially produced from the bioprocessing of crude oil and its fractions in the presence of water. Crude oil in oil fields often times forms an emulsion with water.
An emulsion is a mixture of two or more liquids that are normally immiscible where one phase is discontinuously dispersed in other continuous phase. There are several types of oil/water emulsions including, water-in-oil (w/o) emulsions [water is the dispersed phase, oil is the continuous phase] and oil-in-water (o/w) emulsions [oil is the dispersed phase, water is the continuous phase], as well as more complex emulsions such as water-in-oil-in-water (w/o/w) emulsions and oil-in-water-in-oil (o/w/o) emulsions. More often than not, the emulsions produced in oil fields are w/o emulsions.
In these emulsions, there are a number of surface active molecules that contribute to its viscosity. Further, resistant films at the crude oil/water interface usually form due to the presence many types of interfacial active components (groups, COOH etc.) from the oil phase possessing electrically charges interacting with the ions present in water (H+, OH−, Cl−, etc.). The emulsions in crude oil and its fractions can be formed from the indigenous components.
The high-value biochemicals present or formed or produced in crude oil have diverse applications, including cancer drug application, drilling fluid, cosmetic surgery, and heavy metals removal from drinking water. However, since these indigenous biochemicals are produced in substrates, such as crude oil and its fractions, are highly surface active compounds, they usually create tenacious emulsions in an oil-water system that is very difficult to break (i.e., demulsify). Thus, it is difficult to extract the biochemical from the mixture. In many of these cases, the conventional extraction (demulsification) methods are ineffective due to the high viscosity of the system and strong amphiphilic properties of the surfactants.
Further, while there are some methods for the demulsification of crude oil, these methods typically result in the precipitation of asphaltenes—a type of surface active macromolecules in the oil—which can result in equipment malfunction. Specifically, the precipitation of asphaltenes can cause deposition of asphaltenes in pipelines, and pumps, which can lead to reduced, plugged pipelines, and damaged pumps. Accordingly, it is desirable to avoid asphaltene precipitation.
Thus, there is a need for demulsification methods that are both effective at extracting high-value biochemicals, yet also avoid the precipitation of asphaltenes.